458 Remarks on the Calcutta basin. 



ments of mica-slate, &c. 150 feet below the present surface, 

 and which indicates the latest general change of importance 

 to which the interior of the land and the rivers passing over 

 its surface have been subject. From this to within 45 feet 

 of the surface the changes in the character of the deposits 

 are slight, and indicate a gradual filling up of a basin which 

 had suddenly sunk down to a depth of 75 feet when the 

 coarse quartzose conglomerate was formed. 



The Kankur appears to occur in siliceous clay at a depth 

 of 70 feet, and continues to within 50 feet of ' the surface, 

 where the matrix becomes calcareous. This is succeeded by 

 dark clay with decayed wood to within 45 feet of the surface. 

 Adhesive blue clay, a deposit from marshes, continues to 

 within ten feet of the surface. 



